3
CX-961
2) Tracking error amplifier unit
This tracking error amplifier unit outputs photodetector
output E or F from pin 14 of IC201 (TA2150FN)via an
amplifier and an error amplifier assuming (E - F) as a TE
signal. The low frequency component of voltage TE is
expressed as
TE = (E - F)
×
300 k / 100 k
×
155 k / 328 k
×
82 k / 20 k =
5.8 times.
A TE waveform of approximately 1.51 Vpp is obtained
in the TE output on the basis of Vref. The cutoff
frequency is 44.5 kHz or 29.4 kHz.
1) Focus error amplifier unit
This focus error amplifier outputs photodetector output
(A + C) or (B + D) from pin 16 of IC201 (TA2150FN) via a
differential amplifier and an error amplifier assuming
(A + C - B -C) as an FE signal. The low frequency
component of voltage FE is expressed as
FE = (A + C - B - D)
×
(150 k / 62 k)
×
(60 k / 60 k)
×
(12 k /
60 k) = 4.84 times.
An S curve of approximately 1.45 Vpp is obtained in the
FE output on the basis of Vref. The cutoff frequency is
26 kHz or 133 kHz.
Fig.2:FE CIRCUIT
Fig.3:TE CIRCUIT
